Related Experiment Video
Updated: Mar 1, 2026

Preparing and Injecting Embryos of Culex Mosquitoes to Generate Null Mutations using CRISPR/Cas9
Published on: September 10, 2020
EVOLUTION OF RESISTANCE IN CULEX PIPIENS: ALLELE REPLACEMENT AND CHANGING ENVIRONMENT
Thomas Guillemaud1, Thomas Lenormand1, Denis Bourguet1
1Institut des Sciences de l'Evolution, Laboratoire Génétique et Environnement (C.C. 065), UMR CNRS 5554, Université de Montpellier II, F-34095 Montpellier, France.
Abstract:
Fixation of adaptive mutations in populations is often constrained by pleiotropic fitness costs. The evolutionary pathways that compensate such fitness disadvantages are either the occurrence of modifier genes or replacement of the adaptive allele by less costly ones. In this context, 23 years of evolution of insecticide resistance genes in the mosquito Culex pipiens from southern France are analyzed. The aim of this study is to answer the following points. Is there a fitness cost associated with these resistance genes in natural populations? Does evolution proceed through allele replacement or through selection of modifiers? And finally, how do environmental changes affect the evolution of resistance genes? Samples from the same transect, crossing the boundary between an insecticide-treated and a nontreated area, are analyzed. Clinal analyses indicate a variable fitness cost among the resistance genes and show that allele replacement has been the primary mechanism of resistance evolution in this area. It is also shown that replacement was probably due to environmental changes corresponding to modification in pesticide-treatment intensity.
Related Concept Videos
Mutation, Gene Flow, and Genetic Drift
Genetic Drift
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Transduction
Exon Recombination
Exon shuffling follows “splice frame rules.” Each exon...
What is Natural Selection?

